Rotating damper

ABSTRACT

An adequate rotation angle is ensured and any member is not damaged due to fluid resistance even with use of highly viscous fluid. A rotating shaft ( 2 ) is provided inside a casing ( 1 ) having first divider walls ( 5 ) provided on its inner periphery and in direct or indirect contact with the rotating shaft. Second divider walls ( 4 ) are provided on an outer periphery of the rotating shaft and in either direct or indirect contact with the casing. A flow passage ( 4   a ) is provided in the second divider wall for fluid communication between the pressure chambers. A check valve mechanism has curving portions ( 6   a ) moving on and along the periphery of the rotating shaft and valving portions ( 6   b ) each joining to the curving portion. The curving portion is supported between the rotating shaft and the first divider wall. The flow passage is opened/closed depending upon a direction of fluid flow.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a damper that rotates to moderate rotationalmovement of a cover shifting between open and closed positions or thelike.

2. Description of Related Art

Rotating dampers having a damping function of reducing rotational speedof piano key covers, toilet seats and the like are known, such asdisclosed in Japanese unexamined patent publications No. Hei. 10-211025(hereinafter referred to as “reference 1”) and No. Hei. 9-280290(hereinafter referred to as “reference 2”).

The rotating damper, as described in the references, typically includesa rotating shaft provided in a cylindrical casing, divider walls thatproject from the inner peripheral surface of the casing toward therotating shaft, and blades that project from the outer peripheralsurface of the rotating shaft toward the inner peripheral surface of thecasing. A valve body controls fluid flow between pressure chambers eachdefined by the divider wall and the blade.

More specifically, the valve body is operated to open and close a flowpassage formed in the blade in accordance with a rotating direction ofthe rotating shaft in order to change fluid resistance based on therotating direction. The rotating damper is structured such that therotating shaft rotates at lower speeds when rotating in the directionthat increases the fluid resistance. Therefore, the rotating damper isused in such a manner that fluid resistance decreases when the rotatingshaft rotates in the direction that opens the piano key cover, theseat/seat cover or the like, and the fluid resistance increases when therotating shaft rotates in the opposite direction, for example.

Among such rotating dampers are the ones disclosed in the referencedreference 1 and reference 2.

For example, the aforementioned rotating damper can be used for reducinga lowering speed of a toilet seat to cushion impact. However, recentmainstream toilet seats incorporate heaters, and are therefore heavy inweight. One possible way to reduce the lowering speed of the weightedtoilet seat or other such objects, may be to increase the viscosity ofthe viscous fluid sealed in the casing of the rotating damper. Highlyviscous fluid to be used can include, for example, highly viscousgrease, crude rubber, clay or the like.

However, in structure of the damper described in reference 1, the valvebody mounted on the blade repeats its bending movement in response tofluid pressure produced by rotation of the rotating shaft to open/closethe flow passage. A problem arising in such structure having a valvebody repeating bending movement is that the durability of the valve bodycannot be guaranteed. In particular, when the rotating damper is filledwith highly viscous fluid to provide higher torque, the valve body isplaced under higher pressure, and therefore becomes more susceptible todamage. Hence, a damper in which the flow passage is adjusted by meansof the bending movement of a valve body as described above is inadequatefor use as high torque dampers.

On the other hand, in the damper described in reference literature 2,the valve body is mounted along the outer periphery of the rotatingshaft and allowed to move in a circumferential direction. The valve bodyopens and closes the flow passage formed in the blade. This valve bodydoes not incorporate repetitive bending movement in relation to fluidpressure, and therefore there is no problem of damaging at the bendingportion of the valve body. However, in order to hold the valve bodywithin its traveling range around the rotating shaft, another blade forholding the valve body is provided outside of the blade in which theflow passage is formed and flow in the flow passage is controlled by thevalve body. In other words, the blade for holding the valve body isprovided in the range of relative rotation of the rotating shaft and thecasing.

In the rotating damper as described above, the rotation of the rotatingshaft relative to the casing is limited by obstruction of the blade bythe divider wall. For this reason, if the blade holding the valve bodyprojects from the outer periphery of the rotating shaft as in the damperof reference literature 2, this reduces the rotating range of therotating shaft. If such a damper is filled with highly viscous fluid foruse as a high-torque damper, the thickness of the blade and/or the valvebody must be increased in the circumferential direction in order towithstand high fluid resistance. As a result, a sufficient rotationangle may not be ensured. If the rotation angle is insufficient,problems may yet arise, such as the impossibility of retaining theopening state of the cover that stays in a horizontal position in theclosing state.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a rotating damperwhich is capable of ensuring an adequate rotation angle and hasstructure causing no damage to any member due to fluid resistance,particularly with use of highly viscous fluid.

According to a first aspect of the present invention, a rotating dampercomprises: a rotating shaft that is provided inside a casing and isrotatable relatively to the casing; first divider walls that areprovided on an inner periphery of the casing and in either direct orindirect contact with the rotating shaft; second divider walls that areprovided on an outer periphery of the rotating shaft and in eitherdirect or indirect contact with the inner periphery of the casing; aplurality of pressure chambers defined by the first and second dividerwalls; a limiting mechanism for limiting a flow of fluid between thepressure chambers; a check valve mechanism for permitting a flow offluid in one direction from one pressure chamber to an adjacent pressurechamber, but inhibiting a flow of fluid from the adjacent pressurechamber to the one pressure chamber; and a flow passage provided in eachof the second divider walls for communication of the fluid between thepressure chambers. The check valve mechanism has curving portions thatmove on and along the periphery of the rotating shaft, and valvingportions that each join to the curving portion. Each of the curvingportions is supported between the rotating shaft and the first dividerwall. Depending upon turning movement of the check valve mechanism, eachof the valving portions opens the flow passage for the flow of fluid inthe direction from the one pressure chamber to the adjacent pressurechamber, and closes the flow passage for the flow of fluid from theadjacent pressure chamber to the one pressure chamber.

According to a second aspect of the present invention, a rotating dampercomprises: a rotating shaft that is provided inside a casing androtatable relatively to the casing; first divider walls that areprovided on an inner periphery of the casing and in either direct orindirect contact with the rotating shaft; second divider walls that areprovided on an outer periphery of the rotating shaft and in eitherdirect or indirect contact with the inner periphery of the casing; aplurality of pressure chambers defined by the first and second dividerwalls; a limiting mechanism for limiting a flow of fluid between thepressure chambers; a check valve mechanism for permitting a flow offluid in one direction from one pressure chamber to an adjacent pressurechamber, but inhibiting a flow of fluid from the adjacent pressurechamber to the one pressure chamber; and a flow passage provided in thefirst divider wall for communication of the fluid between the pressurechambers. The check valve mechanism has curving portions that move onand along an inner periphery of the casing, and valving portions thateach join to the curving portion. Each of the curving portions issupported between the casing and the second divider wall. Depending uponturning movement of the check valve mechanism, each of the valvingportions closes the flow passage for the flow of fluid in the directionfrom the one pressure chamber to the adjacent pressure chamber, andcloses the flow passage for the flow of fluid from the adjacent pressurechamber to the one pressure chamber.

The check valve mechanism in the first and second aspects is capable ofbeing made without a member for holding the valve body provided withinthe range of relative rotation of the rotating shaft and the casing. Asa result, a large rotation angle is ensured. Especially, when highlyviscous fluid is used in order for the rotating damper to serve as ahigh torque damper, if each component inside the casing is increased inthickness enough that no damage is incurred from viscous resistance, itis possible to realize the necessary rotation angle.

Further, in the first and second aspects, notches can be formed in oneof three places of the curving portion, the outer periphery of therotating shaft, and an inner periphery of the casing. Timing ofactivation of the limiting mechanism is adjusted in accordance with arelative position of the notch and either the first divider walls or thesecond divider walls.

In the above idea, it is possible to adjust timing when the flowlimiting mechanism functions in accordance with rotation angle.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a sectional view of a rotating damper of a first embodiment.

FIG. 2 is a sectional view taken along the II-II line in FIG. 1.

FIG. 3 is a sectional view taken along the III-III line in FIG. 1.

FIG. 4 illustrates action of the rotation damper of the firstembodiment, in which a rotating shaft rotates clockwise.

FIG. 5 illustrates action of the rotation damper of the firstembodiment, in which a rotating shaft rotates counterclockwise.

FIG. 6 is a sectional view of a rotating damper of a second embodiment.

FIG. 7 is a sectional view taken along the VII-VII line in FIG. 6.

FIG. 8 is a sectional view of a rotating damper of a third embodiment.

FIG. 9 is a sectional view taken along the IX-IX line in FIG. 8.

FIG. 10 is a sectional view of a rotating damper of a fourth embodiment.

FIG. 11 is a sectional view taken along the XI-XI line in FIG. 10.

FIG. 12 is a sectional view of a rotating damper of a fifth embodiment.

FIG. 13 is a sectional view taken along the XIII-XIII line in FIG. 12.

FIG. 14 is a perspective view of the fifth embodiment of the damperwithout a casing.

FIG. 15 is a view when the perspective view of FIG. 14 is cut along theXIII-XIII line in FIG. 12.

FIG. 16 is a view of the damper in which the rotating shaft is rotatedfrom the position shown in FIG. 15 so that a flow passage is opened.

FIG. 17 is a sectional view of a rotating damper of a sixth embodiment.

FIG. 18 is a perspective view of a casing of the rotating damperaccording to the sixth embodiment.

FIG. 19 is a front view of a valve body in a seventh embodiment.

FIG. 20 is a side view of the valve body in the seventh embodiment.

FIG. 21 is a back view of the valve body in the seventh embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5 illustrate a rotating damper of a first embodimentaccording to the present invention.

FIG. 1 is a sectional view along the axis of the rotating damper. FIGS.2 to 5 are cross-sectional views of the rotating damper in a directionperpendicular to a rotating shaft. Incidentally, FIG. 1 is not a crosssection of the rotating shaft 2.

The rotating damper of the first embodiment includes a cylindricalcasing 1 into which a rotating shaft 2 is inserted to allow for relativerotation to the casing 1. An open end of the casing 1 is closed with acap 3. The rotating shaft 2 has a protrusion 2 a formed on a leading endfor insertion, and a flange 2 b formed in a position back from theleading end for insertion.

The casing 1 has a recess 1 a formed at the other end for receiving theinsertion of the protrusion 2 a. The protrusion 2 a is fitted into therecess 1 a and the flange 2 b is attached to and fixed by the cap 3, sothat the rotating shaft 2 is supported.

A pair of blades 4 is formed on the outer periphery of the rotatingshaft 2. A pair of divider walls 5 is formed on the inner periphery ofthe casing 1. Four pressure chambers A, B, C and D are formed in thecasing by the blades 4 and the divider walls 5.

The pressure chambers are varied in capacity by relative rotationbetween the rotating shaft 2 and the casing 1. In the first embodiment,the capacities of the pressure chambers A and C remain equal thoughvariant, as do the capacities of the pressure chambers B and D.

In the blade 4 which creates a partition between the pressure chambers Aand B, a flow passage 4 a passes through in the rotating direction, anda graded step 4 b against which a valve body 6, described later, makescontact is formed. An approximately C-shaped spacer 7 is located on aleading end of the blade 4, and is in direct contact with the innerperiphery of the casing 1. The spacer 7 is combined with the leading endof the blade 4 so that the two move together. The blade 4 is in contactwith the casing 1 via the spacer 7.

In the spacer 7, a flow passage 7 a is formed in a positioncorresponding to the flow passage 4 a formed in the blade 4. A notchportion 7 b is formed in such a manner as to adjoin with the graded step4 b formed in the blade 4, which in turn allows for movement of thevalve body 6.

Thus, the valve body 6 is mounted on the outer periphery of the rotatingshaft 2, and includes curving portions 6 a along the rotating shaft 2,and valving portions 6 b. Each of the valving portions 6 b is joined tothe corresponding curving portion 6 a and extends from the rotatingshaft 2 in the diameter direction.

A pair of band-shaped recesses 2 c is formed on and along the outerperiphery of the rotating shaft 2 in a central portion in the axisdirection. The recess 2 c has a depth equal to the thickness of thecurving portion 6 a. Each of the curving portions 6 a of the valve body6 is fitted into the corresponding recess 2 c so that the curvingportion 6 s winds around the rotating shaft 2. A leading end of each ofthe divider walls 5 provided on the inner periphery of the casing 1comes in contact with the curving portion 6 a. The curving portions 6 aare supported between the divider walls 5 and the rotating shaft 2, sothat the valve body 6 is retained.

The curving portion 6 a has a length in the circumferential directionshorter than that of the band-shaped recess 2 c. When the vavlingportion 6 b comes into contact with the blade 4, a gap 2 d is createdbetween the band-shaped recess 2 c and the end of the curving portion 6a opposite to the valving portion 6 b.

Accordingly, the curving portion 6 a is rotationally movable within therange of the gap 2 d. In other words, the valve body 6 is capable ofrotating relative to the rotating shaft 2 at an angle corresponding tothe gap 2 d. As shown in FIG. 2, when the valving portion 6 b is incontact with the blade 4, the flow passage 4 a is closed. When thevalving portion 6 b is rotated counterclockwise in FIG. 2 on therotating shaft 2 within the range of the gap 2 d, and moves away fromthe blade 4, the flow passage 4 a is opened.

Note that the aforementioned divider walls 5 correspond to first dividerwalls of the present invention. The blades 4 correspond to seconddivider walls of the present invention. The blade 4 is in indirectcontact with the inner periphery of the casing 7 via the spacer 7.

Further, bypass grooves 2 e are formed in portion of the outer peripheryof the rotating shaft 2 on which the curving portions 6 a of the valvebody 6 are not provided (see FIGS. 1 and 3). The bypass grooves 2 efunction as bypasses for establishing communication between the pressurechambers A and D and between the pressure chambers B and C when each ofthe leading end faces of the divider walls 5 partially faces or overlapsthe bypass grooves 2 e.

A portion with the curving portions 6 a of the valve body 6 and a potionwithout the curving portions 6 a are each present on the periphery ofthe rotating shaft 2, but both are herein included in the outerperiphery of the rotating shaft 2.

FIG. 1 also shows O-rings 8 and 9.

Next, the operation of the rotating damper is described with referenceto FIGS. 4 and 5 which are both sectional views taken along the II-IIline in FIG. 1 as in FIG. 2 for illustrating the rotating shaft 2rotated relative to the casing 1. The pressure chambers A and C of thefour pressure chambers A to D are operated in the same manner and thepressure chambers B and D are operated in the same manner. Therefore,the descriptions are herein given mainly using the pressure chambers Aand B for the purpose of clarity.

As shown in FIG. 4, when the rotating shaft 2 rotates clockwise in FIG.4, the pressure chamber A expands, while the pressure chamber Bcontracts in capacity, therefore allowing internal pressure of thepressure chamber B to build up. This built-up pressure acts on thevalving portion 6 b via the flow passage 4 a of the blade 4 of therotating shaft 2, so that the valve body 6 rotates in a direction movingaway from the blade 4. Accordingly, the flow passage 4 a is opened andthe pressure chambers A and B communicate with each other through theflow passage 4 a and the notch portion 7 b.

In the state shown in FIG. 4, the divider wall 5 is placed within rangeof the bypass groove 2 e formed in the outer periphery of the rotatingshaft 2 (see FIG. 3), so that the pressure chamber B also communicateswith the pressure chamber C.

Even if the rotating shaft 2 is rotated in the direction where theinternal pressure of the pressure chamber B is built up in this manner,the fluid in the pressure chamber B will flow into the pressure chamberA via the large flow passage 4 a, and also flow into the pressurechamber C via the bypass groove 2 e serving as a notch dependent uponthe relative position of the divider wall 5. As a result, the rotatingshaft 2 becomes easy to rotate. That is, when the rotating shaft 2 isrotated clockwise in FIG. 4, the flow of the fluid is not particularlylimited.

On the contrary, FIG. 5 shows the state when the rotating shaft 2 isrotated counterclockwise. In contrast to the above case of clockwiserotation, the pressure chamber A is compressed. The fluid pressure inthe pressure chamber A acts on the valving portion 6 b. Thereupon, thevalve body 6 rotates in the direction opposite to the rotating shaft 2.Then, the valving portion 6 b is pressed against the flow passage 4 a toblock the flow passage 4 a. When the flow passage 4 a is blocked, andthe divider wall 5 a is placed within range of the bypass groove 2 e ofthe rotating shaft 2, the fluid in the pressure chamber A flows into thepressure chamber D via the bypass groove 2 e. Resistance at this pointis designed to be much the same as that as when the flow passage 4 a isopened. Hence, in the above range, the damper function is not exerted.Note that, resistance produced when viscous fluid flows through thebypass groove 2 e can be adjusted through the width or depth of thebypass groove 2 e.

The rotating shaft 2 is further rotated counterclockwise in FIG. 5. Inthis case, the bypass groove 2 e moves past the leading end of thedivider wall 5, which then blocks the communications between thepressure chambers A and D and between the pressure chambers B and C viathe bypass grooves 2 e. Thereupon, the fluid in the pressure chamber Aflows into the pressure chamber B via a slight clearance between thespacer 7 and the inner periphery of the casing 1, as well as into thepressure chamber D via a slight clearance between the outer periphery ofthe rotating shaft 2 and the leading end of the divider wall 5. Further,the fluid in the pressure chamber C flows into the pressure chambers Dvia a slight clearance between the spacer 7 and the inner periphery ofthe casing 1, as well as into the pressure chamber B via a slightclearance between the outer periphery of the rotating shaft 2 and theleading end of the divider wall 5.

In this manner, the fluid flow between pressure chambers occurs only viathe slight clearances between the spacer 7 and the inner periphery ofthe casing 1 and the between the outer periphery of the rotating shaft 2and the leading end of the divider wall 5. The fluid flow betweenpressure chambers is limited. That is, the clearance corresponds to aflow limiting mechanism of the present invention. The bypass groove 2 ecorresponds to a notch formed in the outer periphery of the rotatingshaft of the present invention.

When the rotating shaft 2 is rotated counterclockwise in FIG. 5 and thelimiting mechanism functions, the damper function is exerted and therotation of the rotating shaft 2 is slower.

For example, when the rotating damper of the first embodiment is used ina toilet seat or the like, the rotating damper may be mounted in such away that the clockwise rotation of the rotating shaft 2 as shown in FIG.4 is applied as a rotation for raising the toilet seat and thecounterclockwise rotation as shown in FIG. 5 is applied as a rotationfor lowering the toilet seat.

In such a rotating damper, the movable range of the rotating shaft 2 isfrom one point where the blade 4 is in contact with one divider wall 5to a point where the blade 4 comes into contact with the other dividerwall 5.

The valving portion 6 b for closing and opening the flow passage 4 a ismaintained by the curving portion 6 a. For this reason, as compared witha conventional case in which a member for maintaining the valve body isprovided in the pressure chamber, it is possible to ensure a largerotation angle. In particular, when high viscous fluid is used, highpressure acts on the valving portion 6 b of the valve body 6. Therefore,if the thickness of the valving portion 6 b is increased to the extentthat it can withstand the pressure, the movable range is not reduced.

In the first embodiment, the spacer 7 is attached to the leading end ofthe blade 4 of the rotating shaft 2. Without the use of the spacer 7,the leading end of the blade 4 may come into direct contact with or mayapproach the inner periphery of the casing 1. If the blade 4 and thespacer 7 are designed as different members as described above, theclearance between the inner peripheral surface of the casing 1 and thecontact surface of the spacer 7 may be easily produced with precision.

However, if the spacer 7 is omitted or maintains less contact with thecasing 1, it is possible to further extend the rotation range of therotating shaft 2.

In the first embodiment, by providing the bypass groove 2 e, thelimiting mechanism will either act or not act depending on the relativeposition of the divider wall 5 and the rotating shaft 2 when therotating shaft 2 is rotated counterclockwise. In other words, the timingof activation of the flow limiting mechanism is adjusted. However, thebypass groove 2 e is not absolutely necessary. If the bypass groove 2 eis not provided, the limiting mechanism functions at all timesregardless of the relative position of the divider wall 5 and therotating shaft 2 when the rotating shaft 2 is rotated counterclockwise.

A second embodiment illustrated in FIGS. 6 and 7 uses a valve body 10instead of the valve body 6 of the first embodiment. The valve body 10has curving portions 10 a and valving portions 10 b, and a notch 10 isformed in the curving portion 10 a. Another difference from the firstembodiment is that the bypass groove 2 e is not provided in the rotatingshaft 2. Instead of the bypass 2 e that is formed in the rotating shaft2 of the first embodiment, the notches 10 c formed in the curvingportions 10 a serve as a bypass. The remaining structure is the same asthat of the first embodiment, and therefore the same components aredesignated by the same reference numerals as those in the firstembodiment. Description of the individual components is omitted.

Next, operation of the rotating damper in the second embodiment isdescribed.

In the state shown in FIG. 7, the pressure chambers A and B respectivelycommunicate with the pressure chambers D and C via the gaps 2 d and theband-shaped recesses 2 c corresponding to the notches 10 c at theleading ends of the divider walls 5.

The rotating shaft 2 is rotated counterclockwise from the position shownin FIG. 7. Then, the pressure chambers A and C are compressed, and theviscous fluid in the pressure chambers A and C flows into the pressurechambers D and B via the band-shaped recesses 2 c. The rotating shaft 2is further rotated counterclockwise. Then, the entire surfaces of theleading ends of the divider walls 5 separate from the notches 10 c andcome into contact with the curving portions 10 a, whereuponcommunications between the pressure chambers A and D and between thepressure chambers B and C via the band-shaped recesses 2 c are blocked.

In addition, when the rotating shaft 2 is rotated counterclockwise,pressure in the pressure chambers A and C presses the valving portions10 b of the valve body 10 against the blades 4, thereby closing the flowpassages 4 a.

Thus, the fluids in the pressure chambers A and C under high pressureflow into the respectively adjacent pressure chambers B and D via slightclearances between the inner periphery of the casing 1 and the spacers 7provided on the leading ends of the blades 4. Alternatively, the fluidsin the pressure chambers A and C under high pressure flow into therespectively adjacent pressure chambers D and B via slight clearancesbetween the outer periphery of the rotating shaft 2 and the leading endsof the divider walls 5. At this point, the limiting mechanism of thepresent invention functions to exert the damper function.

On the other hand, when the rotating shaft 2 is rotated clockwise, thefluid pressure in each of the compressed pressure chambers B and D actson the corresponding valving portion 10 b via the flow passage 4 a ofthe blade 4. Hence, the valve body 10 rotates counterclockwise withrespect to the rotating shaft at an angle corresponding to the gap 2 d.

That is, the valving portion 10 b moves away from the blade 4 to openthe flow passage 4 a. The fluids in the pressure chambers B and D flowinto their respectively adjacent pressure chambers A and C via the flowpassages 4 a, so that the flow is not limited and the damper function isnot exerted.

In the rotating damper of the second embodiment, the curving portions 10a are supported between the outer periphery of the rotating shaft 2 andthe divider walls 5, thereby maintaining the valve body 10. For thisreason, the rotating damper according to the present invention has noneed of a member for maintaining the valve body 10 within the rotationrange of the rotating shaft as used in conventional devices, and such amember does not narrow the rotation range of the rotating shaft 2. Inparticular, when highly viscous fluid is sealed in order to allow forhigher torque, it is possible to ensure a large rotation angle withoutimpairment of the durability of each component.

A third embodiment shown in FIGS. 8 a and 9 has a pair of blades 11formed on the outer periphery of the rotating shaft 2. The blade 11differs in shape from the blade 4 of the first embodiment, but has thesame function as that of the blade 4. The remaining structure is thesame as that in the first embodiment, and the same components aredesignated with the same reference numerals as those in the firstembodiment. Description of the individual components is omitted.

A flow passage 11 a and a graded step 11 b are formed in the blade 11.The leading end face of the blade 11 is in direct contact with the innerperiphery of the casing 1. Therefore, the spacer 7 of the firstembodiment is not used in the third embodiment, which serves to simplifythe structure.

The rotating damper in the third embodiment operates as in the case ofthe first embodiment. More specifically, when the rotating shaft 2 isrotated clockwise, the valving portion 6 b moves in the range of the gap2 d and separates from the graded step 11 b of the blade 11 so as toopen the flow passage 11 a. Hence, the adjacent pressure chamberscommunicate with each other and the fluid flows unhindered.

On the other hand, when the rotating shaft 2 is rotatedcounterclockwise, the valving portion 6 b blocks the flow passage 11 aof the blade 11. However, while the divider wall 5 is kept facing oroverlapping the bypass groove 2 e formed in the rotating shaft 2 (seeFIG. 8), the fluid flows via the bypass groove 2 e. The bypass groove 2e moves past the divider wall 5, thereupon the limiting mechanismtriggers and the damper function is exerted.

As in the cases of the first and second embodiments, the rotating damperin the third embodiment is capable of ensuring a large angle of relativerotation for the rotating shaft 2 and the casing 1 even when highlyviscous fluid is used.

A fourth embodiment shown in FIGS. 10 and 11 differs from the thirdembodiment in that a flow passage 11 c and a graded step 11 d are formedgenerally along the full length of the side face of each blade 11extending in the axis direction. A valve body 12 of extended length inthe axis direction is used to allow the closing of the flow passage 11c. The step 11 d is formed along the full length of the blade 11, andthe valve body 12 is provided in a range slightly shorter than thelength of the step 11 d. The flow passage 11 c is formed in a rangeslightly shorter than the length of the valve body 12.

The valve body 12 has curving portions 12 a and valving portions 12 b.Each of the curving portions 12 a winds along the outer periphery of therotating shaft 2 and supported between the rotating shaft 2 and thedivider wall 5 of the casing 1. The fourth embodiment is the same as thesecond embodiment in that notches 12 c are formed in the curvingportions 12 a and serve as a bypass. In other words, the flow limitingmechanism according to the present invention triggers or not, dependingupon a relative position of the notch 12 c and the divider wall 5.

The rotating damper in the fourth embodiment operates as in the case ofthe aforementioned embodiments, and a detailed description is omitted.Even if highly viscous fluid is sealed in all pressure chambers A to D,the rotating damper of the fourth embodiment has the same effect ofensuring a large rotation angle without impairing the durability of eachcomponent as that in the aforementioned embodiments.

However, if the flow passage 11 c formed in the blade 11 has the largeopening area as in the case of the fourth embodiment, resistance of theflow passing through the flow passage 11 c is extremely low when thelimiting mechanism does not function, that is, the rotating shaft isrotated clockwise from the position shown in FIG. 11. Therefore, ascompared with the rotating dampers in the aforementioned embodiments,torque generated when the limiting mechanism functions is equal, but itis also possible to more smoothly rotate the rotating shaft 2 when thelimiting mechanism does not function.

A fifth embodiment shown in FIGS. 12 to 16 has structure in which avalving portion 14 b is fitted into a flow passage 13 a formed in theblade 13. The components identical to those in the aforementionedembodiments are designated with the same reference numerals, and adetailed description is omitted.

FIGS. 14 to 16 show the rotating damper without the casing 1. FIG. 14shows the valve body 14 detached from the rotating shaft 2. FIGS. 15 and16 are perspective views of the rotating shaft 2 and the valve body 14attached thereto when cut along the XIII-XIII line in FIG. 12.

The rotating damper of the fifth embodiment has a pair of blades 13provided on the outer periphery of the rotating shaft 2 and a flowpassage 13 a formed in each blade 13.

The flow passage 13 a has one open end facing the pressure chamber Athat is larger than the other open end facing the pressure chamber B,and has an inclined face 13 b extending in the thickness direction ofthe blade 13. The valve body 14 includes a valving portion 14 b thatfits properly into the flow passage 13 a. A leading end of the valvingportion 14 b has an inclined face corresponding to the inclined face 13b. The valve body 14 includes the valving portion 14 b and a curvingportion 14 a. The curving portion 14 a is fitted into the band-shapedrecess 2 c formed in the outer periphery of the rotating shaft 2. Theband-shaped recess 2 c is longer in length than that of the curvingportion 14 a. Therefore, when the valving portion 14 b is fitted intothe flow passage 13 a as illustrated in FIGS. 13 and 15, a gap 2 d iscreated at the end of the curving portion 14 a opposite to the valvingportion 14 b. Accordingly, the valve body 14 is rotatable relative tothe rotating shaft 2 at an angle corresponding to the gap 2 d.

When the rotating shaft 2 is rotated clockwise from the position shownin FIGS. 13 and 15, the valving portion 14 b moves away from the flowpassage 13 a of the blade 13 to open the flow passage 13 a as shown inFIG. 16. Thereupon, the fluid flows from the pressure chambers B and Dto the pressure chambers A and C to allow for smooth rotation of therotating shaft 2.

On the other hand, when the rotating shaft 2 is rotatedcounterclockwise, the pressure of each of the pressure chambers A and Cpresses the valving portion 14 b against the inclined face 13 b of theflow passage 13 a to block the flow passage 13 a. Therein, the relativepositioning of the bypass groove 2 e formed in the rotating shaft 2 andthe divider walls 5 of the casing 1 activates the flow limitingmechanism, resulting in the damper function.

Such a rotating damper is not provided with any member for holding thevalve body 14 opening and closing the flow passage 13 a in the blade 13so that the member would narrow the rotation range of the blade 13.Accordingly, as in the cases of the aforementioned embodiments, it ispossible to provide a large rotation angle, particularly with use ofhighly viscous fluid to allow for higher torque.

In particular, as in the fifth embodiment, if the valving portion 14 bis accommodated within the flow passage 13 a formed in the blade 13, thetotal thickness of the blade and the valving portion can be decreased ascompared with those of the other embodiments. Hence, it is possible toincrease the capacity of each of the pressure chambers, resulting in anincrease in rotation angle.

A sixth embodiment shown in FIGS. 17 and 18 differs from theaforementioned embodiments in that a valve body 16 is provided on theinner periphery of the casing 1, but the sixth embodiment is identicalin all other embodiments in terms of operating the damper.

FIG. 17 is a cross-sectional view at right angles to the rotating shaft.FIG. 18 is a perspective view of the casing 1.

On the inner periphery of the casing 1, divider walls 15 that correspondto the first divider walls of the present invention are provided. A flowpassage 15 a is formed in each of the divider walls 15. Band-shapedrecesses 1 b are formed in portion of the inside wall of the casing 1but not on the divider walls 15.

The valve body 16 includes curving portions 16 a and valving portions 16b. Each of the curving portions 16 a is fitted into the band-shapedrecess 1 b so as to follow the shape of the casing 1. A gap 1 c isformed between the band-shaped recess 1 b and the curving portion 16 a.The valve portion 16 moves in a range of the gap 1 c.

Blades 17 are formed on the outer periphery of the rotating shaft 2. Aleading end of the blade 17 is crowned with a spacer 18. The spacer 18moves together with the blade 17. The curving portions 16 a of the valvebody 16 are supported between the spacers 18 and the casing 1. Notethat, when the pressure chambers A and C come reach a high pressurestate and the pressure acts on the valve body 16 via the flow passages15 a, the valve body 16 moves away from the divider walls 15 and is heldby a sandwiching force required to open the flow passage 15 a.

In the rotating damper of the sixth embodiment, when the rotating shaft2 is rotated counterclockwise relatively to the casing 1, pressure inthe pressure chambers A and C are built up to move the valving portion16 b, resulting in fluid flowing from the pressure chamber A to thepressure chamber D and from the pressure chamber C to the pressurechamber B through the flow passages 15 a.

On the other hand, when the rotating shaft 2 is rotated clockwise,pressure in the pressure chambers B and D is built up, so that thevalving portions 16 b are pressed against the divider walls 15 to blockthe flow passages 15 a. Accordingly, the fluid flows through a slightclearance between the leading end of each divider wall 15 and therotating shaft 2 and a slight clearance between each spacer 18 and theinner periphery of the casing 1. At this point, the flow limitingmechanism functions. That is, the damper function is exerted.

The rotating damper of the sixth embodiment has each curving portion 16a of the valve body 16 supported between the inner periphery of thecasing 1 and the blade 17 by way of the spacer 18. Therefore, as in thecases of the aforementioned embodiments, the range of rotation of therotating shaft 2 is not decreased by a member provided for holding thevalve body. Accordingly, it is possible to ensure a large rotation angleeven when highly viscous fluid is used to allow for higher torque.

FIGS. 19 to 21 show a valve body 19 in a seventh embodiment. The valvebody 19 includes curving portions 19 a and valving portions 19 b, andfurther spring portions 19 c and 19 d are provided at an end of eachcurving portion 19 a. FIG. 19 is a front view of the valve body 19 shownin FIG. 20 when seen from the direction indicated by arrow α. Similarly,FIG. 21 is a back view of the valve body 19 when seen from the directionindicated by arrow β.

Instead of the valve body 6 illustrated in the first embodiment shown inFIGS. 1 to 5, the valve body 19 can be attached to the outer peripheryof the rotating shaft 2. FIGS. 2 to 5 may also be referred to for thefollowing description.

The rotating damper of the seventh embodiment using the valve body 19operates in the same manner as in the rotating dampers of theaforementioned embodiments, and has the same effect of ensuring a largerange of relative rotation for the rotating shaft and the casing.

However, the spring force of the spring portions 19 c and 19 d pressesthe valve body 19 against the blades 4 provided on the rotating shaft 2(see FIGS. 2 to 5). For this reason, when the rotating shaft 2 isrotated clockwise and the fluid pressure acts in the direction where thevalvings 19 b are separated from the blades 4, the valve body 19 movesagainst the spring force to open the flow passages 4 a of the blades 4.However, when the rotating shaft 2 stops, the valve body 19 moves backtowards the blades 4 by the spring force of the spring portions 19 c and19 d. In other words, at the time the direction of rotation is reversed,the valving portions 19 b have already been in a position to close theflow passages 4 a, that is, in a position capable of limiting the flowof fluid. Hence, when the rotating shaft 2 reverses the direction ofrotation at this position, the limiting mechanism of the fluid flow isimmediately initiated.

If such spring portions 19 c and 19 d are not provided, and the rotatingshaft 2 is rotated in the opposite direction from the open state of theflow passages 4 a, time is required for the valve body 19 to move toclose the flow passages 4 a, resulting in the occurrence of so-called“backlash”. However, if the spring portions are provided as in theseventh embodiment, it is possible to prevent such backlash.

Spring portions, such as the spring portions 19 c and 19 d as describedabove, can be provided in any valve body as described in the first tosixth embodiments for prevention of backlash.

As described hitherto, the rotating damper illustrated in each of thefirst to the seventh embodiments need not include any member for holdingthe valve body within the range of rotation of the blade member providedon the rotating shaft, thus allowing for an increase in the rotationangle of the damper. Further, in each of the first to seventhembodiments, the thickness of the divider wall formed on the innerperiphery of the casing 1 is decreased, resulting in a further increasein the rotation angle.

Further, the spacer provided at the top end of the divider wall or theblade in each embodiment may be provided on either the divider wall orthe blade, or neither the divider nor the blade. As matter of course,the spacers may also be provided on both the divider wall and the blade.

Each of the aforementioned embodiments has described examples where therotating shaft rotates relative to the stationary casing. However, therotating shaft and the casing perform relative rotation. Accordingly, ifthe casing is rotated relative to the rotating shaft, the same operationis implemented.

1. A rotating damper, comprising: a rotating shaft (2) that is providedinside a casing (1) and rotatable relatively to the casing (1); firstdivider walls (5) that are provided on an inner periphery of the casing(1) and in either direct or indirect contact with the rotating shaft(2); second divider walls (4, 11, 13) that are provided on an outerperiphery of the rotating shaft (2) and in either direct or indirectcontact with the inner periphery of the casing (1); a plurality ofpressure chambers (A, B, C, D) defined by the first and second dividerwalls; a limiting mechanism for limiting a flow of fluid between thepressure chambers; a flow passage (4 a, 11 a, 11 c, 13 a) provided ineach of the second divider walls (4, 11, 13) for communication of thefluid between the pressure chambers; and a check valve mechanism forpermitting a flow of fluid in one direction from one pressure chamber ofthe pressure chambers to an adjacent pressure chamber of the pressurechambers, but inhibiting a flow of fluid from the adjacent pressurechamber to the one pressure chamber, the check valve mechanismcomprising: curving portions (6 a, 10 a, 12 a, 14 a, 19 a) moving on andalong the periphery of the rotating shaft (2), and each supportedbetween the rotating shaft (2) and the first divider wall (5); andvalving portions (6 b, 10 b, 12 b, 14 b, 19 b) each joining to thecurving portion (6 a, 10 a, 12 a, 14 a, 19 a), wherein depending uponturning movement of the check valve mechanism, each of the valvingportions (6 b, 10 b, 12 b, 14 b, 19 b) opens the flow passage (4 a, 11a, 11 c, 13 a) for the flow of fluid from the one pressure chamber tothe adjacent pressure chamber, and closes the flow passage for the flowof fluid from the adjacent pressure chamber to the one pressure chamber.2. A rotating damper, comprising: a rotating shaft (2) that is providedinside a casing (1) and rotatable relatively to the casing (1); firstdivider walls (15) that are provided on an inner periphery of the casing(1) and in either direct or indirect contact with the rotating shaft(2); second divider walls (17) that are provided on an outer peripheryof the rotating shaft and in either direct or indirect contact with theinner periphery of the casing; a plurality of pressure chambers (A, B,C, D) defined by the first and second divider walls (15, 17); a limitingmechanism for limiting a flow of fluid between the pressure chambers; aflow passage (15 a) provided in the first divider wall (15) forcommunication of the fluid between the pressure chambers; and a checkvalve mechanism for permitting a flow of fluid in one direction from oneof the pressure chambers to an adjacent pressure chamber of the pressurechambers, and inhibiting a flow of fluid from the adjacent pressurechamber to the one pressure chamber, the check valve mechanismcomprising: curving portions (16 a) moving on and along an innerperiphery of the casing (1) and supported between the casing (1) and thesecond divider wall (17); and valving portions (16 b) each joining tothe curving portion (16 a), wherein depending upon turning movement ofthe check valve mechanism, each of the valving portions (16 b) opens theflow passage (15 a) for the flow of fluid from the one pressure chamberto the adjacent pressure chamber, and closes the flow passage (15 a) forthe flow of fluid from the adjacent pressure chamber to the one pressurechamber.
 3. A rotating damper according to claim 1, wherein notches (2e, 10 c, 12 c) are formed in one of three positions of the curvingportion (6 a, 10 a, 12 a, 14 a, 19 a), the outer periphery of therotating shaft (2) and an inner periphery of the casing (1), and timingof activation of the limiting mechanism is adjusted in accordance with arelative position of the notch and either the first divider walls (5) orthe second divider walls (4, 11, 13).
 4. A rotating damper according toclaim 2, wherein notches are formed in one of three positions of thecurving portion (16 a), the outer periphery of the rotating shaft (2),and the inner periphery of the casing (1), and timing of activation ofthe limiting mechanism is adjusted in accordance with a relativeposition of the notch and either the first divider walls (15) or thesecond divider walls (17).